Refrigerator control



. 3, 1940. R. w. JOHNSON REFRIGERATOR CONTROL Filed Feb. 11, 1938 2 Sheets-Sheet l INVENTOR 94 R. w. JOHNSON 2,224,053

REFRIGERATOR CONTROL Filed Feb. 11, 1938 2 Sheets-Sheet 2 INVENTOR Patented Dec. 3, 1940 UNITED STATES REFRIGERATOR CONTROL Roy W. Johnson, Milwaukee, Wis assignor to Allyne Laboratories, Inc., Cleveland, Ohio, a

corporation of Ohio Application February 11, 1938, Serial No. 190,087

10 Claim.

This invention relates to a method and cer-' tain devices used for controlling the operating cycle of an intermittent absorption refrigeration machine.

In a machine of this type, the temperature in.

There-is a practically straight line relationship between these minimum and maximum points. In other words, the indicated shut-01f temperature will vary in direct proportion with the room temperature.

Hitherto there has been no satisfactory manner, other than manual operation, for obtaining the required regulation of generator shut-off temperature in response to inevitable variations in room temperature in the vicinity of the machine.

Since the intermittent absorption type refrigerators in use previous to my invention are generally operated by the use of kerosene or similar fuel, it has been the practice to close the fuel supply valve at one predetermined generator temperature and to open said valve when the charge of the refrigerant in the evaporator of the machine had become exhausted, permitting a rise n temperature in the compartment. Automatic functioning apparatus could be provided for performing the method last outlined but only at the expense of poor fuel economy and sub-freezing refrigerating compartment temperatures.

If the ambient temperature fell below the optimum for the apparatus setting, there would be a highly undesirable waste of refrigeration. On the other hand, if the ambient temperature rose above this optimum,'there would be danger of insuflicient refrigeration. Only by varying the shut-off temperature of the generator with the ambient temperature can efficient intermittent operation be obtained.

An object of the invention is to provide a mechanism actuated by thermostats for opening and closing a fuel valve supplying fuel to the burner of the still of a refrigeration system, the

opening of the valve being controlled by the temperature in the evaporator and the closing of the valve by the temperature in the still.

V Another object of the invention is to provide convenient means for adiusting'themaximum temperature in the evaporator of a refrigeration system and automatically adjusting for fast or slow operation of the system, depending on the rise or fall in temperature outside of the system.

Another object is to provide snap action of the fuel valve so that it will be maintained in either a fully open or fully closed position.

A further object is to provide a mechanism such that a small increase in-temperature in the evaporator will open the fuel valve, irrespective of the setting or adjustment ofthe evaporator thermostat.

The control device or mechanism of the present invention includes three thermostatic elements. One of these elements positioned in close proximity to the evaporator of such a machine, a second thermostatic element is located in the still-absorber, and the third element is placed without the machine so as to respond to changes in room temperature. Each element comprises a bulb filled with a liquid having a suitable coefficient of expansion, and is connected to an otherwise sealed bellows.

The bellows which is connected to the thermostatic bulb associated with the evaporator or refrigeration compartment is operable to open a valve which supplies kerosene or other fuel to a main burner which heats the still-absorber. A pilot burner (not shown herein) is operated continuously from a separate fuel supply.

Closing of the fuel supply valve is accomplished by expansion of the bellows which is associated with the second thermostatic element, located within the still-absorber.

An intermittent operation of the machine is obtained by use of the two bellows which respectively cause the fuel supply valve to be opened or closed. An appropriate rise in temperature in the refrigeration chamber will cause the fuel valve to open. The main burner will then operate steadily until it has produced an increase in temperature within the still-absorber, at which time the other bellows will operate to close the fuel valve. Before the fuel valve is closed, an amount of ammonia or other refrigerant vapor suflicient to provide a desired refrigerating effect for a selected period will have been transferred from the stillabsorber to the evaporator.

A novel. method of controlling and varying the refrigerating cycle of such a machine is entailed in the function of the third'thermostatic bulb which is responsive to changes in ambient temperature. Through suitable mechanism, which will be specifically described, this third bulb and an associated bellows operate to modify the action of the still-absorber thermostatic bulb in closing the fuel valve. As the room temperature rises, the closing of the fuel valve will be deferred progressively to keep the still-absorber operating for longer periods. Conversely, a lower room temperature will have the effect of hastening the closing of the main fuel valve.

The present method has for its essence the regulation of the temperature in a still-absorber automatically and simultaneously in response to variations in room temperature.

Suitable manual adjustments are provided for setting the fuel valve opening bellows to give a desired maximum evaporator temperature and for regulating the valve closing bellows to respond to a selected temperature in the still-absorber.

There is incorporated in the automatic control mechanism of this invention a ratchet which is associated with the bellows for opening the fuel valve under all conditions. when the fuel valve is first opened by 'a manually operated latch member which is provided, it is very likely that the valve-opening bellows will be in an extremely distended position due to an abnormally high evaporator temperature, corresponding closely to room temperature. Under these circumstances, it is improbable that the lowest evaporator temperature on the first cycle will reach the normal turn-on point of, say, 31 degrees. It is the function of the ratchet to accommodate the control mechanism in its special position and to insure cycling until normal operating conditions are reached.

With the above'and other objects in view, the invention may be said to comprise a novel method of refrigeration control and a mechanism as illustrated in the accompanying drawings hereinafter described and particularly set forth in the appended claims together with such variations and modifications thereof as will be apparent to one skilled in the art to which the invention appertains.

Reference should be had to the accompanying drawings in which: I r

Fig. l is a diagrammatic view showing parts of a refrigeration system based on the absorption principle with the present invention connected thereto;

Fig. 2 is an elevational view of the upper portion of the control device with parts broken y;

Fig. 3 is a sectional view taken on the line 3-3 of Fig. 2; and

Fig. 4 is a sectional view taken on line l4 of Hg. 1.

Referring in detail to the drawings, in which like reference numerals refer to like parts throughout the several views, the control device is designated generally by the numeral II. It is connected by a fuel supply pipe II to a fuel tank l2 and by pipe l3 to a burner l4. While the present invention is shown as applied to a refrigerator using liquid fuel, it should be understood that it may be applied to a system using gaseous fuel, in which case the control device would be connected to a gas main or other source of supply. Burner |4 supplies heat to a still-absorber i5 which is connected to a cooling coil 18 and to an evaporator II by piping l3,

The control device III is connected by tubing 20 to a thermostat bulb 2| positioned in a suitable well in the shell of the still-absorber l5. A second thermostat bulb 22 is positioned in the evaporator l1 and connected to control device ID by tubing 23. A third thermostat bulb 24 may be placed in any convenient place where it will be exposed to "room temperature. Bulb 24 is connected to control device I by tubing 25.

As shown in Figs. 2, 3, and 4 the control device ||l comprises a system of thermostatically operated levers enclosed in a casing 38, and fuel regulating valves contained in a fuel chamber 3|. Formed on the lower part of chamber 3| is a cylindrical portion containing a second cham ber 32. Within the second chamber 32 a screen 33 of tubular form is disposed so as to strain fuel entering from the pipe H. The recess 32 is arranged to discharge fuel through a, needle valve 33a into the interior of chamber 3|. A float 34 fulcrumed on pin 35 controls the needle valve 33:: to maintain a constant level of fuel in the chamber 3|.

Flow of fuel to the burner 4 is controlled by a valve 31, comprising a seat 38 and a plunger 39. The seat 38 is secured in the upper end of a short tubular extension 3|a formed on the bottom of chamber 3|, the tubular extension communicating with the pipe I 3 leading to the burner l4. The seat 38 is disposed below the liquid level maintained by the float 34 so that when the plunger 39 is raised from the seat 38 fuel may flow downward and into pipe l3, through an opening 35 near the bottom of the extension 3|a.

Plunger 39 extends upwardlyinto the casing 30 through a cup 48 containing a liquid seal at the top of the fuel chamber 3|, and is urged downwardly against seat 38 by a compression spring 4| interposed between the bottom of cup 4|] and a collar 42 on said plunger.

Within the casing 38 the upper end of the plunger 39 has fonned on its upper end a button-like head 45, the under side of which may be engaged by a. finger 48 on a lever 41. Lever 41 is fulcrumed on a pin 48 secured to the casing 33, and has a projection 49 formed on the end which is remote from finger 45. An extensible toggle link 58 such as is commonly used in snap action mechanisms. comprising a compression spring 50a disposed between opposed conical end plates 58b and 580, is interposed between projection 43 on lever 41 and a projection |a on a second lever 5|. Lever 5| is also fulcrumed on pin 48. Both levers 4'1 and 5| are of substantially channel shaped cross section with web portions cut away to permit movement of associated parts, lever 5| being made narrower than lever 41 so that its leg portions are inside the leg portions of lever 41, as shown in Fig. 3. Also pivoted on pin 48 is a third lever 52 having formed on one end a toothed segment 53. Segmeat 53 may be engaged bya pawl 54 pivoted on a pin 55 carried by leg portions of the lever 5|. Lever 52, at its end which is remote from segment 53, has formed thereon a conical de-- 68 between the leg portions thereof, and acts as a stop for pawl 54. Attached to the bottom of casing 38 is a leaf spring 6| with an inverted U-shaped portion Iila at its end so disposed as to engage bottom edge 62 of pawl 54 when lever 5| carrying the pawl is in its lowermost position (as in Fig. 4) and to urge pawl 54 into engagement with segment 53, overcoming the effect of torsion spring 59. The teeth on segment 53 are so shaped that with downward movement they pass under the pawl, but with upward movement they may be engaged by pawl 54, thus raising the pawl and lever 5| therewith. When so engaged, levers 5| and 52 act as a unit, moving about the axis of pin 48. The range of upward movement through which pawl 54 may engage segment 53 is limited by abutment means in the form of an extension 63 on spring 6|, engaging a lug 64 formed on the bottom of casing 38. It is not possible for the spring 6| to urge pawl end 62 after its extension 63 is stopped by lug 84.

A second vertical push rod 18 which is parallel to push rod 56 is arranged on the opposite side of pin 48 to counteract movements of push rod 58 by engaging bridge 68 of lever 5|. Push rod 18 is connected to the free end of athermostat bellows 1|. Thermostat bellows 51 is connected by tubing 23 to bulb 22, and thermostat bellows 1| is connected by tubing 28 to bulb 2|.

It will be evident that as the temperature in evaporator I1 increases, bellows 51 will be expanded to exert a downward thrust on push rod 56, thus tending to move levers 52 and 5| in a clockwise direction as viewed in Fig. 4, provided segment 53 and pawl 54 are engaged. If the movement continues, a position will be reached where the axis of the extensible link 58 will intersect the axis of pin 48. A further movement in a clockwise direction will cause lever 5| to snap to its uppermost position, while at the same time causing lever 41 to move in a counterclockwise direction, so that finger 48 on lever 41 will raise plunger 39, thus admitting fuel to burner I4.

Fig. 4 illustrates the relative arrangement of the levers at the beginning of such a movement as just described, in which case the fuel valve 31 is closed. Fig. 2 illustrates the relative arrangement corresponding to an open valve supplying fuel to burner I4.

With an increase of temperature in the stillabsorber I5, bulb 2| will cause bellows 1| to expand, thus causing a downward movement of push rod 18, which by pressing on bridge 68 will cause lever 5| to move in a counter-clockwise direction. After passing dead center, lever 5| will snap to its lower-most position, thus causing lever 41 to move in a clockwise direction to close valve 31 and stop the flow of fuel to burner I4. Fig. 4 represents the condition of the mechanism when the valve 31 is closed.

It will be understood from the above description that bellows 1| can only function to close valve 31 and bellows 51can only function to open valve 31.

To limit the clockwise movement of lever 41 upon closingof i the valve 31, an extension is formed thereon below finger 46 for engaging a boss formed on the bottom of casing 38. Movement in the opposite direction is limited by a depending lug 16 formed on the other end of lever 41 engaging the bottom of casing 38.

Movement of the lever 5| is limited by engagement with an ofiset portion 11 formed on the bottom of a latch member 18 extending through the top of casing 38 and joined to a handle 19,

and by engagement with a lug 88 formed on a bearing plate 8| secured to casing 38. A slotted guide member 8|a insideof the casing 38 restrains the latch member 18.

Movement of lever 52 clockwise is limited by a lug 82, which depends from an end thereof, engaging the bottom of casing 38, and counterclockwise by the lower end of segment 53 engaging the top of lug 84.

Latch member 18 provides a convenient means of opening the valve 31 to start the operation of burner I4.

To provide for varying the range of temperature through which bellows 51 may operate, a manual adjustment is provided as follows: A lever 85 of generally channel-shaped cross-section is fulcrumed on a pin 88 carried by the casing 38 and bearing plate 8| (Fig. 3). One end 81 of the lever 85 is formed to seat a coil compression spring 88, which encircles the rod 55 and presses against the free end of bellows 51, thus tending to prevent expansion of said bellows 51. The opposite end of lever 85 engages the inclined surface of a cone 89a formed on the end of a screw 89, which is threaded through an end of the casing 38. A finger grip or handle 98 is provided on the end of screw 88 which is outside the casing 38. Inward or outward movement of the screw 89 causes greater or less compression of the spring 88, thus varying the temperature range over which the bellows 51 will function. Stops 9| and 92 on the finger grip 98 and casing 38, respectively, engage to limit rotation of the screw 89.

Adjustment of the temperature point at which the bellows 1| closes valve 31 is obtained by means of a screw device comprising a nut 95 threaded through a boss 95a formed on the hearing plate 8|. The nut 95 has a cylindrical bore which receives the rod 18. Extending between nut 95 and a collar 96 on push rod 18 is a compression spring 91 which tends to prevent expansion of bellows 1|. An opening 85a in the lever 85 provides a clearance for the adjustment nut 95 and spring 91.

An automatic adjustment is provided for modifying the effect of spring 91 on bellows 1| so that an increase in temperature in bulb 24 will require a higher temperature in bulb 2| before bellows 1| can close fuel valve 31. This consists of a bellows I88 attached to the top of casing 38 with its free end pressing against the upturned end |8I of a lever I 82 fulcrumed on the pin 86. Lever I82 is of channel shaped cross section and lies inside the leg portions of the channel shaped lever 85. A compression spring I83 which is positioned between levers 85 and I82 has the effect of counteracting expansion of the bellows I88 by urging end |8I of lever I82 against the lower extremity of said bellows I88. Bellows I88 is connected to bulb 24 by tubing 25. At the end of lever I82 remote from end IN, the side walls of the lever are slightlyupturned to form lugs I84 which are disposed one on either side of push rod 18 and spring 96 so that the lugs I84 will engage collar 98 after push rod 18 has moved a slight distance downward in response to expansion of bellows 1|. Thus it will be seen that as bellows I88 expands, lever I82 will move counterclockwise about pin 86 and lugs I84 will be raised. If now bellows 1| expands, collar. 98 will engage lugs I84 which will assist spring 91 in counteracting bellows 1|, with the result that a higher temperature in bulb 24 will require a higher temcounter-clockwise as viewed in Fig. 1.

perature in bulb 2I before bellows H can actuate the snap action levers 41 and 5I to close the fuel valve 31. A slight compression and yielding of bellows I00 will result from the downward pressure of collar 96 on the lugs I04 of lever I02.

It will be noted furthermore that the effect of bellows I in modifying the operation of bellows H is varied somewhat by adjustment of the screw 89. As the end of lever adjacent screw 89 is raised, the spring I03 between lever I02 and 85 will be compressed, thus requiring a higher temperature in bulb 24 before bellows H is affected.

For example, to maintain a lower temperature at evaporator I1, the screw 9| would be turned The counteracting effect of spring 88 on bellows 51 would thus be decreased, permitting a lower temperature in bulb 22 to cause opening of valve.31. At the same time the counteracting effect of spring I03 on bellows I00 is increased.

It will be appreciated that the spring 88 as sociated with bellows 51 is very much stronger than the spring I03 which resists expansive movement of bellows I00.

A summary of the operation of the control device of this invention will now be given.

The burner I4 will heat the still-absorber I5 until a predetermined amount of ammonia or other refrigerant gas has been driven off. It has been noted that the rise in temperature of the still-absorber I5 will be proportional to the amount of ammonia driven off. When the temperature of the still-absorber I5 reaches a predetermined maximum, the expanding liquid in the thermostat bulb 2I and tubing 20 will actuate bellows 1|. Expansion of the bellows 1| will move the rod 10 downward against the resistance of spring 91. The downward movement of rod 10 will cause lever 5| to rotate in a counterclockwise direction which will, through the toggle link 50, produce a clockwise rotation of the lever 41. Such movement of the lever 41 permits spring M to close the valve 31 and shut off the supply of fuel to burner I4.

After the device has been started initially by manual operation of the latch member 18, it will be automatically started thereafter by the thermostat bulb 22 in the following fashion.

When the temperature in the evaporator I1 becomes too high, indicating exhaustion of the refrigerant, the fluid in thermostat bulb 22 will expand bellows 51 and push the rod 56 downward against the force of spring 88. This movement of the rod 56 will produce clockwise rotation of the lever 52 having the toothed segment 53 on one end. The corresponding upward motion of segment 53 will cause a similar movement of the pawl 54 which it engages. As a result of the upward motion of pawl 54, lever 5I will be snapped into an elevated position (Fig. 2) by the toggle link 50. The end of the lever 41, which carries the projection 49 will be forced into its lower-most position (Fig. 2) as lever 5| is elevated, and the finger 48 on the other end of said lever 5| will rise suddenly and open the fuel supply valve 81.

Due to the cooperating relations which have been stated, it will be seen that the pawl 54 will engage the toothed segment 53 only when valve 31 is in closed position.

By using a toothed segment 53 instead of only a single tooth, it is possible to insure turning on of the burner I4 irrespective of the room temperature at the thermostat bulb 24. If the room temperature is exceptionally high, for example degrees Fahrenheit, bellows 51 will remain in a partially expanded condition during the initial operation of the evaporator I1. In this event, the toothed segment 53 will be kept in a correspondingly high position and the pawl 54 will engage a lower tooth on said segment 53 when the valve is closed in response to a suitably high temperature in the still-absorber I5.

As has been indicated, the bellows I80 which is connected to the thermostat bulb 24 is responsive to changes in the ambient temperature. An increase in room temperature will cause a corresponding expansion of the bellows I00. When this occurs, the upturned end IOI of lever I02 will be pushed downwardly, raising the lugs I04 on the other end of said lever, and thereby providing greater resistance to downward movement of the rod 10 which is responsive to the still-absorber thermostat bulb 2I.

Therefore, it will be apparent that the higher the room temperature, the longer will be the operating period of the still-absorber I5, and the greater will be the amount of refrigerant available for cooling purposes.

These latter results, it will be observed, are obtained through an, automatic operation of mechanism and occur simultaneously with an increase in ambient temperature.

To control in a predetermined manner the temperature in the refrigeration compartment or evaporator I1, it is necessary only to rotate the screw 89 in a proper direction. That is to say, clockwise rotation of screw 89 as seen in Fig. 1 will cause the end 81 of lever 85 which seats the spring 88 to move upwardly and compress said spring, so that a higher temperature in the evaporator I1 will be required to expand ghe bellows 51 sufllciently to open the fuel valve An opposite rotation of screw 88 will decrease the compression of spring 88 and permit the fuel valve 31 to be opened by a lower temperature in the evaporator I1.

It is to be understood that the particular form of apparatus shown and described, and the particular procedure set forth, are presented for purposes of explanation and illustration and that various modifications of said apparatus and procedure can be made without departing from my invention as defined in the appended claims.

What I claim is:

1. In an intermittent absorption refrigeration system, having an evaporator, a still-absorber, a fuel burner, and a fuel supply valve in operative relationship,- the combination which includes: thermostatically-operated means associated with the evaporator for opening the fuel supply valve, thermostatically-operated means connected to the still-absorber for closing the fuel supply valve, thermostatically-operated means responsive to room temperature and including a pivoted lever which is spring biased for modifying the action of the means for closing the fuel supply valve, and an individual screw device for adjusting the said valve closing means.

2. In an intermittent absorption refrigeration system, having an evaporator, a still-absorber, a fuel burner, and a fuel supply valve in operative relationship, the combination which includes: thermostatically-operated means associated with the evaporator for opening the fuel supply valve and including a bellows and a push rod, thermostatically-operated means connected to the stillabsorber for closing the fuel supply valve and including a bellows and a push rod, thermostatically-operated means responsive to room temperature for modifying the action of the means for closing the fuel supply valve and including a bellows, and an intermediately pivoted lever having one end engaging the bellows of the modifying means and its other end engaging a portion of the push rod of the closing means, the three bellows being arranged in parallelism.

3. In an intermittent absorption refrigera ion system, having an evaporator, a still-absorber, a fuel burner, and a fuel supply valve in operative relationship, the combination which includes: thermostatically-operated means associated with the evaporator for opening the fuel supply valve, thermostatically-operated means connected to the still-absorber for closing the fuel supply valve, thermostatically-operated means responsive to room temperature for modifying the action of the means for closing the fuel supply valve, and manually controlled means for adjusting the means for opening the fuel supply valve, said manually controlled means including an intermediately pivoted lever and a conical-ended screw for varying the position of said lever.

4. In an intermittent absorption refrigeration system, having an evaporator, a still-absorber, a

fuel burner, and a fuel supply valve in operative relationship, the combination which includes:

thermostatically-operated means associated with room temperature for modifying the action of the means for closing the fuel supply valve, a casing for the several thermostatically-operated means, and a separate member accessible externally of the casing for manually operating the means for opening the fuel supply valve.

5. In an intermittentabsorption refrigeration system, having an evaporator, a still-absorber, a fuel burner, and a fuel supply valve in operative relationship, the combination which includes: thermostatically-operated means associated with the evaporator for opening the fuel supply valve,

thermostatically-operated means connected tothe still-absorber for closing the fuel supply valve, and thermostatically-operated means responsive to room temperature for modifying the action of the means for closing the fuel supply valve, each thermostatically-operated means including a bellows; adjusting means for varying the action of the fuel supply valve opening and closing means; and a separate member for manually operating themeans for opening the fuel supply valve, said separate member in its normal inoperative position being arranged to limit movement in one direction of a portion of the valve closing means.

6. The combination in an absorption refrigeration machine having a fuel valve of a bellows for opening the fuel valve, a bellows for closing the fuel valve, a bellows for controlling the operation of the bellows for closing the fuel valve, a spring for each bellows acting to resist the expansion thereof, and means for adjusting simultaneously the resisting actions of the springs for the bellows for opening the fuel valve and the bellows which controls the operation of the bellows for closing said valve.

7. In combination with a fuel valve, a control device comprising a bellows for opening the fuel valve. a bellows for closing the fuel valve, a bellows for controlling the operation of the bellows for closing the fuel valve,a spring for eachbellows acting to resist the expansion thereof, and means for adjusting simultaneously the resisting actions of the springs for the bellows for opening the fuel valve and the bellows which controls the operation of the bellows for closing said valve.

8. The combination in an absorption refrigeration machine having a fuel valve of a bellows for opening the fuel valve, a bellows for closing the fuel valve, a bellows for controlling the operation of the bellows for closing the fuel valve, a spring for each bellows acting to resist the expansion thereof, means for adjusting simultaneously the resisting actions of the springs for the bellows for opening the fuel valve and the bellows which control the operation of the bellows for closing said valve, and means for adjusting independently the resisting action of the spring for the bellows for closing said valve.

9. An absorption refrigeration control device comprising, in combination, a bellows for opening a fuel supply valve; a bellows for closing the fuel supply valve; a bellows for restraining the operation of the bellows which closes said valve; two push rods, one connected to each of the valveclosing and valve-opening bellows; a first pivoted lever having one end engaging the push rod of the valve opening bellows and having a toothed segment on its other end; a second lever pivoted coaxially with the first lever and engaging the fuel valve with one end; a snap action toggle mechanism in engagement with the other end of the second lever; a third lever pivoted at one end coaxially with the first lever, connected to the second lever by means of the toggle mechanism and having a portion intermediate its length positioned to engage the rod of the bellows which closes the fuel supply valve: a pawl pivoted on the third lever and engaging the toothed segment of the first pivoted lever; and a fourth lever pivoted intermediate its ends and engaging the movable portion of the restraining bellows with one end and with the other end the push rod operated by the valve closing bellows.

10. An absorption refrigeration control device comprising, in combination, a bellows for opening a fuel supply valve; a bellows for clodng the fuel supply valve; a bellows for'restraining the operation of the bellows which closes said valve; two push rods, one connected to each of the valve closing and valve opening bellows; a first pivoted lever having one end enga n the push rod of the valve opening bellows and having a toothed segment on its other end; a second lever pivoted coaxially with the first lever and the fuel valve with one end; a snap action toggle mechanism in engagement with the other end of the second lever; a third lever pivoted at one end coaxially with the first lever, connected to the second lever by means of the toggle mechanism and having a portion intermediate its length positioned to engage the rod of the bellows which closes the fuel supply valve: a pawl pivoted on the third lever and engaging the toothed segment of the first pivoted lever; abutment means for releasing the pawl from the toothed segment: and a fourth lever pivoted intermediate its ends and engaging the movable portion of the restraining bellows with one end and with the other end the push rod operated by the valve closing bellows.

ROY W. JOHNSON. 

